Windows 7 Connectivity Issues

Hello, Recently my laptop hasn't been able to connect to one of my wireless routers in my house, and it used to be able to.

I have two wireless routers, one being a talk talk router, and the other being a Belkin router.

My laptop connects fine to the talk talk router, but doesn't connect to the Belkin router, it doesn't pick it up either.

On the odd occasion it does pick it up, but when i try to connect to it, it either disappears, or says Unable to connect.
When we go to troubleshoot it, it says the wireless adapter isnt working, but it must do seeing as it can connect to any other network.

I have tried using a external wireless adapter and that doesn't work either.
I dont think its the router either because everyone else in the house can connect to it.

I have tried running a virus scan and it picked up nothing, i have tried reformatting it with the build in recovery system, but this did not work either.

I might try installing a brand new clean version of windows 7 just to see if that fixes it.

has anyone got any ideas before i go ahead with the reformat?
Thanks for replying in advance